This invention relates to an electrophotographic apparatus for forming or printing a duplicated image of a document at any desired position on a record carrier comprising means for exposing or exposing and scanning the document to produce an imagewise modulated light ray, a charge retentive member for retaining an electrostatic charge image formed thereon on the basis of said imagewise modulated light ray, means for driving the charge retentive member through a transfer section, means for feeding a record carrier through the transferring section at which the record carrier is positioned opposite to the charge retentive member, and means for transferring the charge image with or without being developed with toners onto the record carrier at said transferring section.
In known electrophotographic apparatuses the following means have been used for exposing or exposing and scanning a document to be copied onto an electrophotographic photosensitive member.
(1) A document is placed on a reciprocally movable document table and is exposed and scanned by a fixedly arranged optical system.
(2) A document is placed on a fixedly arrangement document table and is exposed and scanned by a movably arranged optical system.
(3) A document is placed on a fixedly arranged document table and is exposed by a fixedly arranged optical system in a one-shot manner.
(4) A document is fed by a document feed device comprising document feed rollers and is exposed and scanned by a fixedly arranged optical system.
(5) A document is fed to a given position on a document table by a document feed device comprising a feed belt which moves on the table along its surface and then is exposed and scanned by a movable optical system.
(6) A document is fed into a given position on a document table by a document feed device and is then exposed by a fixedly arranged optical system in a one-shot manner.
The exposing device and the exposing and scanning device belonging to the above mentioned groups (1) to (3) can be generally used, because they can handle thick documents such as books as well as thin sheet like documents. While the exposing or exposing and scanning devices of the groups (4) to (6) are mainly used for the thin sheet like documents, and have a special advantage that they can handle the sheet like documents in a very efficient manner. For the sake of simplicity the exposing device and the exposing and scanning device will be termed as an exposure-scanning device hereinafter.
With the aid of the exposure-scanning device an electrostatic charge image corresponding to the document image is formed on a charge retentive member such as an electrophotographically photosensitive member. Then the charge image is transferred onto a record carrier such as a record paper with or without being developed with toners. For the sake of simplicity the charge image and the toned image on the charge retentive member are sometimes termed as a duplicated image. In the known electrophotographic apparatus the exposure-scanning means, means for driving the charge retentive member and means for feeding the record carrier to the transferring section are always controlled in a fixedly operable manner relative to each other. That is to say they are so constructed and controlled that a front end of the duplicated image corresponding to a front end of the document image should always coincide with a front end of the record paper.
In practice one side edge of the record paper should be remained without being copied in order to obtain a space for binding, and the document image or a portion thereof should be duplicated at a given position on the record paper. In case of using the exposure-scanning means belonging to the groups (1) to (3) since the document can be placed on the document table at any desired position the above mentioned variations can be achieved to some extent. As shown in FIG. 1 the document table 1 of such an exposurescanning means comprises a glass stage 2. One side edge 3 of the glass stage 2 is made coincident with one side edge of an effective picture frame and corresponds to the front edge of the record paper. Therefore if a document 4 shown by a broken line in FIG. 1 is placed on the table with its one side being made coincident with the edge 3 of the glass stage 2, the duplicated image of the document can be formed at a given position on the record paper.
There is further provided on the document table a mark or stopper (not shown) for positioning the document in a direction perpendicular to the edge 3. Usually the document table 1 is made flat and the document can be displaced on this flat surface in orthogonal directions shown by double arrows A and B. Therefore it is possible to form a duplicated image at any desired position on the record paper. However in this case it is quite difficult to place the document on the table at such a position that in the final copy the image of the document will be formed at a desired position on the record paper. Particularly if it is required to form a portion of the document image at a center position or deviated position on the record paper, the operation for placing the document on the table becomes extremely cumbersome, because in this case the document has to be set on the table with masking the document except for the given desired portion to be duplicated with a white paper or with folding the document in such a manner that the given portion to be copied is exposed.
In the known electrophotographic apparatus comprising the exposure-scanning means of the groups 4) to 6) the position of the document image on the record paper could not be displaced with respect to the paper viewed in the paper feeding direction. In the direction perpendicular to the paper feeding direction the position of the image on the paper can be displaced to some extent by inserting the document at a shifted position in the relevant direction.
In this manner in the known electrophotographic apparatuses the position of the duplicated image with respect to the record carrier could not be shifted at will, particularly in the feeding direction of record carrier.